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My car is currently at dealership and I've been told my resistors are going bad. Sadly they say the front clam has to come off to fix this, so I passed on getting it done due to labor costs. Can this mod actually be done without removing the clam? I'm planning on living in Miami and reeealy want my A/C working, but geeeze not if it costs labor for clam removal...

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I can be done without removing clam but requires cutting (and patching) a sizable hole out of the ac recirculation panel in front of the brake pedal. Theres a few threads on here with that procedure if you search.

Removing and replacing the clam is only a fraction of the job, getting all the HVAC pieces out and back in is a chore and the AC system needs to be evacuated, reassembled and recharged correctly. if you're not comfortable with all that, you might want to leave it to a pro.
 

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As a side note I would suggest get everything the way you want it clam off, was going to play with some alternate resistor values and seriously over estimated access to the area in the Exige. Nevermind.....maybe next time.


I did some testing on the bench,[I have a spare heater and distribution box] and I think a 1 ohm for low and a .33 ohm for medium would be a nice improvement. doesn't matter much if you do 1 or 1.33 for low the difference is small. Guess I will have to tolerate my knuckles freezing until I have the clam off again or more patience.
 

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Just keeping you guys updated. Received the DC controller from China. I think I'm going to start a new thread at some point to make the info easier to find, but here is the preliminary results:
It actually arrived fairly quickly considering customs and all that. It's not fully installed yet because I've been wrestling with a leak issue, but initial testing on the bench shows a few things:

The pot doesnt fit and mount like OEM into the pod, its much smaller, but will fit with a washer to assist. The stalk is much smaller and not a half moon, so it mounts off center and spins in an elliptical path and not stay centered. Doesn't bother me that much at the moment, just mounting it so that its centered on full blast but will probably want to replace it eventually to have it centered. I could try machining it down but the stalk is so thin to begin with I don't think that approach will work. It is a 22k ohm and appears similar or exact to this: https://www.amazon.com/uxcell®-WH5-1A-Carbon-Composition-otentiometer/dp/B00A0FUU9G Probably shouldn't be that hard to replace with something that matches a little better. I don't know much about electronics to know what tolerances I have with the ohm range etc. I can tell you that at least 1/3 of the range at the bottom isn't usable as it doesn't supply enough voltage to power the blower. So even though its an infinite adjustment range, it occurs over less of the knob travel so really only a modest improvement of adjustability over the stock 3 positions.
Im not an engineer but my testing with my bench battery charger so far shows that it doesn't deliver the full input voltage to the output even on max setting when under load. It seems to be dropping about 1.5 - 2 volts under load which results in significantly less airflow from the blower on full. Have to see if this results in an actual airflow difference when installed. If so, my plan is to install a bypass switch under the dash just in case to bypass the full current directly to the blower as did the OEM switch. Not optimal and may have to continue looking for better DC controller, but such is the life of the test pilot.

Wont be much of an update for a while as I have a leak in my condenser outlet and need to pull the whole shebang out and get it repaired. In vying for the boneheaded move of the week, I forgot to hold the second nut when removing the condenser ac line and it twisted and ruptured. Hopefully it can be repaired and not replaced.

Mav
 

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Look on one of the Tony Wa type mod threads I think there is a p/n for a pot with a push switch that may integrate nicely in your setup
 

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Also, read into how PWM works before you spend too much time measuring the output voltage. You'll need to use either an oscilloscope or a resistor-capacitor low pass circuit. That should make sense once you get a good understanding of how those things work.


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I did the Tony Wa mod, that's a 10k ohm 1/2 watt linear taper. This controller came with a 22k (or 2.2k?), not sure of the wattage. All it says on it is L1 WH5-1A A22K. I think changing the ohms would allow the rotation to get more usable range, since it cuts out about 2/3, but as mentioned, thats where my knowledge of electronics ends. CYOW5, you seem to know something about these things, any suggestions?
 

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Also, read into how PWM works before you spend too much time measuring the output voltage. You'll need to use either an oscilloscope or a resistor-capacitor low pass circuit. That should make sense once you get a good understanding of how those things work.


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I read up a little on PWM. I probably have more questions now than answers, but it seems what you're saying is although it shows lower output than the input current, this is false information? I don't have an oscilloscope but seat of the pants airflow with/without the DC controller seemed lower with. I'll have to buy something that actually measures airflow to know for sure.
 

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I was hoping Wikipedia would have a good article, but it just looks like someone tried to make it as complicated as possible. It's actually pretty simple - the controller is just a very fast on/off switch. It probably even says how fast in the specs. If it is fast enough, it can turn on and off fast enough that the motor can't tell that it is pulsing. However, since it is off a period of time, less power gets to the motor. For example, a 50% duty cycle means it is on only half the time, so the motor runs (roughly) at half power. So you can't measure the voltage output - the voltmeter can't read fast enough. Now, at 100% duty cycle, you should be able to read the voltage since it is permanently switched on at that point. That also means that it shouldn't be any slower than running no controller at all when asking for full power. The potentiometer itself should not be handling any real power (a huge flaw in the OE design), and it is probably expected to just make a 0-5v signal to the controller at nearly no current.


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That's pretty much what I gathered. But I did all the measuring at what should be full power, at least that was as far as I could turn the potentiometer. I measured what the blower was drawing from my 12v (10a) battery charger and got about 9.5v on the output wires going to the blower. Then I measured again with the source connected to the DC controller at full power, there was about a 2 v drop in output = 7.5v. I didn't have an anemometer at the time (just ordered one off amazon) but it definitely sounded like less airflow when the current dropped.
 

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10a may not be enough, on the bench I have measured 12 amps

check it with a real battery

If it is a 22k then I will bet the 10k will be perfect, if it was 2.2 then a 1k would work. I think it is a 22k

When you have your ac working well, don't underestimate how low you want the fan, it gets cold!
 

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perfect, I have the 10k ohm pot that I took off the temp control when I did the Tony Wa bypass. Obviously its got the right shaft on it.

Its not that its 10amp or 12amp, it's that the current drops regardless of whether I have it set to 10a or 2amp.

This unit says maximum output is 300W, that sounds like a lot but it could it be that its not enough at full power:

Input voltage : 12V DC
Maximum Output power: 300W
Maximum current: 30A
Overload Current: 60A
PWM pulse width modulation range: 0% - 100%;
 

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I think I'm going to start a new thread at some point to make the info easier to find
Google searches tend to go to this thread, so it might be best to leave it here.

The pot doesn't fit and mount like OEM into the pod, its much smaller, but will fit with a washer to assist. The stalk is much smaller and not a half moon, so it mounts off center and spins in an elliptical path and not stay centered.
Thanks for that. It sounds very similar to the one I bought a while back but didn't end up installing in the car.

...I forgot to hold the second nut when removing the condenser ac line and it twisted and ruptured. Hopefully it can be repaired and not replaced.
Have you ever used Alumaweld? It's an aluminum brazing rod that works with a propane torch. Harbor Freight sells the rod or you can get them on the internet. Practice on some scrap aluminum first, but it's not hard as long as the the brazing material can't pour out of the spot you are trying to repair. You'll see what I mean when you try it or you can see it on YouTube videos. This is basically how AL radiators are made anyway. Often the side tanks are welded, but the core to the tanks are brazed on.
 

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perfect, I have the 10k ohm pot that I took off the temp control when I did the Tony Wa bypass. Obviously its got the right shaft on it.



Its not that its 10amp or 12amp, it's that the current drops regardless of whether I have it set to 10a or 2amp.



This unit says maximum output is 300W, that sounds like a lot but it could it be that its not enough at full power:



Input voltage : 12V DC

Maximum Output power: 300W

Maximum current: 30A

Overload Current: 60A

PWM pulse width modulation range: 0% - 100%;

Your charger though might be where the drop is coming from. Have you measured the input and output voltage at the same time? I bet you'll see they are the same and the charger just can't supply enough current, so the voltage drops.


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re: ac condenser

look at my thread started under my pre password debacle username for part numbers and images for using a Vintage Air condenser and lines, the stock one is upside down and while it may be possible to remove the brackets and drill some holes to reuse it, I don't think it is worth the trouble.

IT is supposed to be in the 90's here tomorrow so I can finally get some high stress measurements on my system mods

http://www.lotustalk.com/forums/f313/2007-exige-ac-heater-rework-348738/index2.html
 

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Roundabout. Thanks for the info. I was near a harbor freight this morning so I bought the alumi weld rods. I also called a few radiator and auto ac repair shops. They both said the same thing "hell no". They said they can't be repaired when they're used due to the oil inside. I think the alumiweld will work, my only concern right now is the size of the repair. You can see from the pic it's not really a small crack but more like a small aluminum vagina. I don't know how to get the alumiweld in the gap without dripping it into the tubing. I need to build it up a little at a time which I don't think is going to work with this.
 

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Update

OK, I was able to bend the tubing back a little and close up the gap. Going to clean it up good and give this a go. Anyway to test this under pressure before investing all the hours in reinstalling it ?
 

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I have used the stuff before, and it does work, but it is really really really close to the melting point of aluminum, and once it actually does start to bond with the aluminum, it lowers the whole areas melting point and can go poof in a hurry,s o you end up with a melted blob.

Find a guy with a TIG welder
 

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it really shouldn't be a problem. Aluminum needs over 1000 degrees and this stuff melts at 730. I'll use a map torch and my infrared heat gun and just keep it below 800 and I think it will be ok.
 

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as an example
lead melting point: 621 deg F
tin melting point: 449 deg F
63/37 lead tin solder melting point 361 deg F

that is what happens as soon as your aluminum welding stuff mixes with the aluminum, it will lower the melting point of the entire molten mixture instantly

I am not saying it wont work, but that I have used it and this is what you have to deal with
 

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I have used the stuff before, and it does work, but it is really really really close to the melting point of aluminum, and once it actually does start to bond with the aluminum, it lowers the whole areas melting point and can go poof in a hurry,s o you end up with a melted blob.
I have seen this as well when my kids were using it to make a frame for a robot, although, I haven't melted anything as of yet. I have a lot of experience soldering and it's really similar. The area needs to be clean and scuffed with a wire wheel or something similar. I would try to close up the hole as much as possible by possibly peening the hole shut with a small punch. The rod material will become liquid-like, but will also spread with some surface tension, so it only drips in my experience when too much is applied. As you heat it evenly, try scratching the rod against the surface. It is OK to leave the heat on while you do this. Do not leave the rod in the heat and try to melt it that way. The most important thing is that the work piece be up to temp. The braze is strong on the finished piece, probably even strong enough to bend and twist the part after you're done. Practice is important, because you won't want to try to heat it a second time as the low melting point of the material will cause it to drip away. Perhaps you could also braze it from the underside so that it can't drip inside.
 
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